In a typical aircraft electrical generating system, the aircraft engine, which operates over a range of speeds, drives a generator through a constant speed drive (CSD). The frequency of the generator is compared with a reference frequency to establish a control signal for the CSD, maintaining a constant steady state frequency. A typical speed control has a proportional integrator circuit which combines the error signal with an integral of the error signal to provide the CSD control signal. The generating system is subject to transient frequency deviation with changes of load and input speed.